Section (3) pcre2sample
PCRE2 — Perl-compatible regular expressions (revised API)
PCRE2 SAMPLE PROGRAM
A simple, complete demonstration program to get you
started with using PCRE2 is supplied in the file
pcre2demo.c in the
src directory in the PCRE2 distribution. A
listing of this program is given in the pcre2demo(3) documentation. If
you do not have a copy of the PCRE2 distribution, you can
save this listing to re-create the contents of
The demonstration program compiles the regular expression that is its first argument, and matches it against the subject string in its second argument. No PCRE2 options are set, and default character tables are used. If matching succeeds, the program outputs the portion of the subject that matched, together with the contents of any captured substrings.
If the -g option is given on the command line, the program then goes on to check for further matches of the same regular expression in the same subject string. The logic is a little bit tricky because of the possibility of matching an empty string. Comments in the code explain what is going on.
The code in
an 8-bit program that uses the PCRE2 8-bit library. It
handles strings and characters that are stored in 8-bit code
units. By default, one character corresponds to one code
unit, but if the pattern starts with (*UTF), both it and
the subject are treated as UTF-8 strings, where characters
may occupy multiple code units.
If PCRE2 is installed in the standard include and library directories for your operating system, you should be able to compile the demonstration program using a command like this:
cc -o pcre2demo pcre2demo.c -lpcre2-8
If PCRE2 is installed elsewhere, you may need to add
additional options to the command line. For example, on a
Unix-like system that has PCRE2 installed in
/usr/local, you can compile the
demonstration program using a command like this:
cc -o pcre2demo -I/usr/local/include pcre2demo.c -L/usr/local/lib -lpcre2-8
Once you have built the demonstration program, you can run simple tests like this:
./pcre2demo _zsingle_quotesz_cat|dog_zsingle_quotesz_ _zsingle_quotesz_the cat sat on the mat_zsingle_quotesz_ ./pcre2demo -g _zsingle_quotesz_cat|dog_zsingle_quotesz_ _zsingle_quotesz_the dog sat on the cat_zsingle_quotesz_
Note that there is a much more comprehensive test program,
supports many more facilities for testing regular expressions
using all three PCRE2 libraries (8-bit, 16-bit, and 32-bit,
though not all three need be installed). The pcre2demo(3) program is
provided as a relatively simple coding example.
If you try to run pcre2demo(3) when PCRE2 is not installed in the standard library directory, you may get an error like this on some operating systems (e.g. Solaris):
ld.so.1: pcre2demo: fatal: libpcre2-8.so.0: open failed: No such file or directory
This is caused by the way shared library support works on those systems. You need to add
(for example) to the compile command to get round this problem.
Last updated: 02 February 2016 Copyright (c) 1997-2016 University of Cambridge.
This manual page is taken from the PCRE library, which is distributed under the BSD license.